This invention relates to an air spring and shock absorber module, and more particularly, the invention relates to a shock absorber damping adjustment mechanism based upon air spring load.
Vehicles utilize shock absorbers to dampen vibrations and shocks experienced by a vehicle. Variations in load and ground conditions can affect vehicle control and handling. As a result, it is desirable to have the ability to selectively adjust the damping force in the shock absorber to improve vehicle control and handling as these variable change.
Vehicles utilizing air spring suspensions have combined the air spring and shock absorber into a single module to minimize the required space for the units and to save on bracket weight and cost. It is desirable for these modules to have the shock damping adjusted based upon the load carried by the air springs so that the damping corresponds to the vehicle load. Shocks have typically been calibrated to provide damping to the vehicle when fully loaded, however, this results in an over-damped suspension for conditions in which the vehicle is less than fully loaded. Prior art designs have connected an air line between the air spring and the shock absorber so that the air spring pressure may be utilized to adjust the damping of the shock absorber. A valve assembly has been mounted on the side of the shock absorber to receive the pressure from the air line. The valve assembly typically used is rather large and protrudes from the side of the shock absorber resulting in clearance issues, cost to manufacture and attach the housing, and vulnerability to damage. The external air lines are prone to damage. Large housing size is required to obtain the force from the air pressure to hold the damping settings because the mechanism is not isolated from fluid flow valve opening forces within the damper. Therefore, what is needed a compact adjustable damping device that receives the pressure from the air spring to adjust the damping based upon vehicle load.
This invention relates to a suspension assembly including a shock absorber having a housing filled with hydraulic fluid. An air spring is supported on the shock absorber, and the air spring includes a bladder filled with air. A valve assembly is surrounded by the fluid housing and the bladder. The valve assembly is in fluid communication with the hydraulic fluid and air. The air manipulates the valve and adjusts flow of hydraulic fluid through the shock absorber to adjust damping based upon vehicle load experienced at the air spring. Preferably the valve assembly is located within the inner cylinder head arranged between the piston rod and the outer cylindrical wall of the shock absorber. The valve assembly may include a teeter-totter valve that cooperates with other valves and springs to provide variable damping throughout the vehicle load experienced by the inner spring. Alternatively, a linear two positioned valve may be used to change the damping in response to a predetermined pressure within the air spring corresponding to a particular vehicle load.
Accordingly, the above invention provides a compact adjustable damping device that receives the pressure from the air spring to adjust the damping based upon vehicle load.